ASA 125th Meeting Ottawa 1993 May

4pAO10. Use of the vector Bragg wave-number scattering condition to
measure turbulence.

Louis Goodman

Diane Sargowicz

Naval Undersea Warfare Ctr., Newport, RI 02841

John Oeschger

Steven Letcher

Univ. of Rhode Island, Kingston, RI 02881

Peter Hebda

Americom Corp.

Acoustic scattering that satisfies the far-field Born approximation leads
to a simple linear relationship between the scattered pressure field and the
scattering field, namely the two are Fourier transform pairs. A set of
laboratory experiments have been devised to exploit this relationship for the
case of scattering from a turbulent field. Data are taken in a multiple
scattering angle configuration such that the Bragg wave-number vector
associated with each scattering angle pair is in the same direction. Use of
broad bandwidth source and receiver transducers (250 to 750 kHz) then allows a
three-dimensional fully resolved wave-number spectra of the turbulent field to
be estimated. Results are presented for scattering from a turbulent buoyant
plume. The data can also be used to examine the validity of the fundamental
assumption of the far-field Born approximation.